This invention relates to condition sensing cable devices useful in oceanographic work, and more particularly to an improved cable construction of the type comprising a plurality of hydrophones or other transducers spaced along a cable to form a line array.
Devices of the foregoing character are at times deployed by streaming horizontally from a moving tow vessel, and at times are suspended vertically in the water. In any event, size, weight, and particularly flexibility of the cable type of line array device are important factors affecting ability to handle, deploy, recover, and store the device using available deck machinery and without the requirement of additional special handling equipment. Another important consideration is the capability of the cable array, and particularly the wire conductors and transducer elements, to withstand the bending, flexing, and jerking forces imposed by either being towed from a vessel or suspended from a buoy subjected to surface wave action.
A variety of hydrophone cable or line array devices have been used or proposed in the past having a plurality of discrete sensors spaced therealong. Examples include those described in U.S. Pat. No. 3,518,677 to E. F. Florian, and No. 3,531,760 to W. A. Whitfill, Jr. All of the foregoing are relatively complex, expensive, and as a very important consideration are not readily made up or changeable on site as to transducer number and location along the cable.
Among recent materials advances that have contributed to lighter, stronger and more flexible electroacoustic cable devices is that of aramid fibers which are characterized by their strength, high resistance to stretch, their lightness in weight, and their flexibility. U.S. Pat. No. 3,939,464 to R. C. Swenson, the inventor herein, discloses a cable sensor mount in combination with a cable comprising aramid fibers formed in four sections, each separately covered, and a plurality of groups of conductors lying in the interstices between the fiber sections, the cable sections and conductors all being held together and protected by a braided cover of nylon, or the like. The sensor mount comprises a cylindrical, open, sensor housing framework or cage, preferably of stainless steel, and a pair of relatively short tapered flexible polyurethane cones or fairings fixed to opposite ends of the cage. The mount is inserted between or among the fiber sections that have been spread apart and lie in four parallel grooves defined in the cage and fairings. The cage structure comprises split ring ends connected by grooved strongbacks and fastened to additional end rings by screws. The end rings comprise formed extensions of the strongback grooves and are aligned with the grooves in the flexible fairings.
While the just described cable and sensor mount construction has provided a notable improvement over the earlier mentioned prior art with respect especially to versatility and flexibility, the cable and sensor mount structures are rather complex, expensive to manufacture bulkier and less flexible than desired.